Release coating compositions comprising a diorganopolysiloxane and an organosiloxane block copolymer



United States Patent O 3,308,030 RELEASE COATING COMPOSITIONS COMPRISING A DIORGANOPOLYSILOXANE AND AN R- GANOSILOXANE BLOCK CGPOLYMER Sharon R. Haenni, Midland, Mich., assignor to Dow Corning Corporation, Midland, Mich, a corporation of Michigan No Drawing. Filed Jan. 4, 1965, Ser. No. 423,384 36 Claims. (Cl. 260-291) This invention relates to a release coating comprising an organosiloxane resin and a dimethylpolysiloxane fluid.

Removing foods burned on various surfaces which'have been involved in the cooking of foods has been a problem for housewives since stoves were invented. Today there are many" aids to help the housewife remove the charred food from the surfaces of stoves, ovens and cooking utensils. These aids include strong detergents, scouring pads, steel wool, scraping devices, high potency solvents, ammonia and caustic. Because ovens are especially susceptible to contact with foods which char and adhere firmly to the oven surface, the most difficult problem a housewife has in cleaning the cooking area is cleaning the oven. Once the food becomes charred on the oven surface its removal is a major task which is anything but pleasant for the housewife. The housewife now has available special oven cleaning aids which include various combinations of strong detergents, high p0- tency solvents, ammonia and caustic. Such aids are dangerous to have around the house, because many of the ingredients can cause severe burns, blindness and even death. The housewife does not find such cleaning aids desirable especially if there are children in the home. There are other safer methods which can be used to remove the char from the oven surface, but these are difficult for a housewife to use. These aids include rubbing with steel wool and detergent, scraping and rubbing.

The real need for a housewife is not to have the charred food so firmly adhered to the oven surface that drastic measures for cleaning are required. The present invention provides the housewife with a composition which can be applied to the oven surface to aid in the removal of any food dropping and charring thereon.

An object of the present invention is to provide a release material suitable for use in an oven which is clear and preferably colorless, which is heat stable and does not decompose below 600 R, which is easy to apply,- which is durable and will last and be effective over a long period of time without loss of properties and release repeatedly from the same spot, which firmly adheres to 1 the surface and still is readily removable, which has excellent release properties for charred food, which has good shelf stability, which is stain resistant, which is easy to reapply either partially or entirely, and which is economical. Another object is to provide a release material composition applicable from aerosol packages. Another object is to provide an emulsion of a release material. These and other objects will become apparent from the following detailed description of the present invention and the appended claims.

The present invention relates to a release material consisting essentially of (A) a diorganopolysiloxane of the unit formula R,,(OH) SiO wherein R is a monovalent radical selected from the group consisting of alkyl radicals, alkenyl radicals and aryl radicals, n has an average value from 1.98 to 2.0024 inclusive, at least 90 percent of the silicon atoms having two methyl radicals per silicon atom bonded to the silicon atom through silicon-carbon bonds, In has an average value of not more than 0.02, the sum of m|+n does not exceed 2.0024, said diorganopolysiloxane having a viscosity of at least 50,000 cs. at 25 0, there being no more than 2 mol percent RSiO units and SiO units.

of the units with alkenyl radicals attached to the silicon atom through silicon-carbon bonds, (B) a block copolyrner consisting essentially .of (l) polymer blocks of the average structure [(CH SiO] [R' SiO] [RSiO wherein R is a rnonovalent radical selected from. the group consisting of methyl, ethyl, vinyl and phenyl radicals, the sum of s-|t+u has an average value from 6 to 100 inclusive and t and it each have a value of up to 10 percent of the sum of s+t+u, (2) polymer blocks of the average unit formula (0 1-1 (CH SiO wherein q has an average value from 1 to 1.25 inclusive, w has an average value of up to 0.25 inclusive and the sum of q+w does not exceed 1.25, the siloxane unitsin (l) beingfrom 10 to 75 mol percent and the siloxane units 2) being from 25 to 90 mol percent of the total siloxane units in said block copolymer, the minimum mol percent, of siloxane units (2) when the sum of s-i-t-l-u has an average value of from to 100 being determined by the equation 50M/S+0.1S=30, where M is the minimum mol percent of siloxane units (2) and S is the sum of s+t+u, there being present 15 to 95 inclusive weight percent of (A) and 5 to 85 inclusive weight percent of (B), each based on the combined weight of (A)+(B).

The release materials of the present invention are prepared by mixing the two ingredients in any conventional manner.

Thediorganopolysiloxane (A) is essentially a dimethylpolysiloxane of the unit formula R (OH) SiO where n'has an average value from 1.98 to 2.0024, In has an average value of not more than 0.02, preferably n has an average value from 1.98 to 2.0020 inclusive. Preferably m has an average value of not more than 0.0024. The sum of m+n does not exceed 2.0024, preferably the sum of m +n does not exceed 2.0020. Particularly useful diorganopolysiloxanes are those in which n has an average value from 2.00 to 2.0020 inclusive.

The diorganopolysiloxane (A)v has approximately two silicon-bonded monovalent organic radicals per silicon atom. The diorganopolysiloxane (A) is composed essentially of R SiO units but can also have R SiO units, The diorganopolysiloxanes (A) are soluble in organic solvents conventionally used for organosiloxanes. When units other than 'R SiO are present, they should not be present in amounts such that the diorganopolysiloxane loses its essentially linear character and so that the value of n falls outside the required range. Preferably, R SiO RSiO and 'SiO units are present in no more than 5 mol percent. The most desirable diorganopolysiloxanes (A) are those having the structural formula R SiO[R 'SiO] SiR wherein p is an integer having an'average value greater than 845, prefer+ ably p has an average value greater than 1,010. A particularly preferred range of p for aerosol compositions is from 845 to 1635. Other preferred operable diorganopolysiloxanes are those having a structural formula HO[R SiO] H wherein 2 has the same values-as above.

Another preferred operable diorganopolysiloxanes (A) are those having the structural formula HO[R SiO] SiR wherein-p has the same values as defined above. By definition the diorganopolysiloxanes are either R Si0 endblocked or OH endblocked; The average unit formula in which n has a value greater than 2.000 requires that there be present R SiO endblocking groups. The larger the. value of 21, when n exceeds 2.000, the smaller the average molecular weight of the diorganopolysiloxane (A). The diorganopolysiloxane (A) is usually composed of a mixture of polysiloxanes of varying molecular weights having an average value such that the above limitations are maintained. Because the diorganopolysiloxane (A) is usually a mixture, the exact value of p as defined above is an average value. The value of p is difiicult to measure, therefore the size of the polysiloxane can best be deter- Y 3 mined by viscosity. The viscosity of the diorganopolysiloxane (A) should be at least 50,000 cs. at 25 C. If the viscosity is less than 50,000 cs. at 25 C., the release material no longer has satisfactory release properties. Preferably, the viscosity is at least 100,000 cs. at 25 C.

I The diorganopolysiloxane (A) must have at least 90 mol percent of the organosiloxane units present as dimethylsiloxane units and preferably at least 95 mol percent dimethylsiloxane units. The monovalent radicals, R; are for example, alkyl radicals such as methyl, ethyl, propyl and hexyl; alkenyl radicals such as vinyl or allyl; aryl radicals such as phenyl, tolyl, xylyl or naphthyl; the preferred monovalent radicals for R are methyl, phenyl and vinyl. Not more than percent of the silicon atoms should be bonded to monovalent radicals other than methyl radicals. Diorganopolysiloxanes (A) containing less than 90 mol percent dimethylsiloxane units do not provide a polysiloxane with satisfactory heat stability and durability. The diorganopolysiloxane (A) should not have more than 2 mol percent alkenyl radicals as greater amounts reduce the release properties of the release material such that little or no release property remains.

The diorganopolysiloxane (A) of the present invention can contain hydroxyl radicals bonded to the silicon atoms through a silicon-oxygen bond. The hydroxyl radicals preferably are present only as endblocking groups, but operable diorganopolysiloxanes can have up to 0.02 silicon-bonded hydroxyl radicals per silicon atom. When the amount of hydroxyl radicals per silicon atom is greater than 0.02, the release material has a tendency to cure. The release material when cured on a surface is very difficult to remove from the surface to which it has been applied. The diorganopolysiloxane (A) can be composed of the organosiloxane units such as dimethylsiloxane, trimethylsiloxane, m-onomethylsiloxane, monophenylsiloxane, phenylmethylsiloxane, diphenylsiloxane, phenyldimethylsiloxane, vinyldimethylsiloxane, vinylrnethylsiloxane, monovinylsiloxane, ethylmethylsiloxane, tolylrnethylsiloxane, ethyldimethylsiloxane, and SiO The preferred organosiloxane units are dimethylsiloxane, trimethylsiioxaneand monomethylsiloxane.

' The block copolymer (B) is composed of polymer blocks (1) having a structure wherein R is a monovalent radical selected from the group consisting of methyl, ethyl, vinyl and phenyl. The sum of s+t+u is from 6 to,100 inclusive and t and u each have a value up to 10 percent of the sum of s+t+u. The lower limit of the sum of s+t+u required is 6 in that the essential block copolymer properties are lost when less than 6 siloxane units are present. The specific characteristics of the block copolymers are critical in the present invention. When the sum of s+t+u exceeds 100, the resulting products are inoperative. Preferably, the sum ofs-l-H-u is from to 75 inclusive and most preferably the sum of s+t+u is from 20 to 50 inclusive. The polymer blocks should be essentially dimethylsiloxane. Small amounts of other units containing methyl, ethyl, vinyl and phenyl radicals can be tolerated when present in amounts preferably less than 10 mol percent of the total siloxane units of (1). Such units can be phenylmethylsiloxane, diphenylsiloxane, vinylmethylsiloxane, diethylsiloxane, ethylmethylsiloxane, phenylethylsiloxane, monophenylsiloxane, monomethylsiloxane, monoethylsiloxane, and monovinylsiloxane. Therefore, 2 and u are not greater than 10% of the sum of s+t+u. Preferably, theR SiO and RSiO units are present in amounts less than 5 mol percent. When other units replace the dimethylsiloxane units in polymer block 1), the location of these units in the polymer chain is not critical. Most preferably the polymer block (1) contains only dimethylsiloxane units.

The polymer block (2) has the average unit formula (C H (CH SiO wherein q has an average value from 1 to 1.25 inclusive, and w has an average value up to 0.25, and the sum of q-l-w does not exceed 1.25. Preferably, q has an average value from 1 to 1.20 inclusive, w has an average value up to 0.20 and the sum of w-t-q does not exceed 1.20. Polymer blocks (2) are mainly composed of monophenylsiloxane units, but other units such as phenylmethylsiloxane, monomethylsiloxane, and diphenylsiloxane units can also be present in amounts less than 25 mol percent based on the total number of units in polymer block (2). The location of phenylmethylsiloxane, diphenylsiloxane and monomethylsiloxane are not critical in the polymer block (2). It is preferred that polymer block (2) contain from 2 to 20 mol percent, based on the total number of siloxane units of (2) of phenylmethylsiloxane units. Thus, q has an average value from 1 to 1.8 inclusive, w has an average value from 0.02 to 0.20 inclusive, and the sum of q+w does not exceed 1.20. The best results are achieved with from 4 to 15 mol percent phenylmethylsiloxane units. Thus, q has an average value from 1 to 1.11 inclusive, w has an average value from 0.04 to 0.15 inclusive and the sum of w+q does not exceed 1.15. The average size of the polymer block (2) is dependent on the average size of blocks (1) and the mol percentage of (1) and (2).

It has been found that when these variables are fixed, that the average block size of (2) is also fixed and, therefore, specification of the block size of (2) is redundant.

The block copolymer (B) is composed of 10 to mol percent based on the total number of siloxane units of polymer block (1). When less than 10 mol percent of polymer block (1) is present, the release material has very poor release properties and has unsatisfactory durability. When more than 75 mol percent of the block copolymer is composed of (1) units, the release material hasunsatisfactory release properties. The maximum mol percent of (1) units present in the block copolymer is closely related to the average number of siloxane units per block 1). Particularly, when the average number of siloxane units per block (1) is from 50 to 100 inclusive units the block copolymers (B) are essentially composed of two types of blocks, specifically those blocks containing essentially dimethylsiloxane units (1) and those blocks containing essentially monophenylsiloxane units (2). Where essentially monophenylsiloxanes includes up to 25 mol percent phenylmethylsiloxane units when the mol percent of either (1) unit or (2) units is fixed, the other mol percent is immediately known. The minimum mol percent of siloxane units (2) when the average number of units per block (1) is from 50 to 100 units is determined by the equation 50M/S+0.1S=30, where M is the minimum mol percent of siloxane units (2) and S is the sum of s+t+u. The maximum mol percent of siloxane units (1) when the average number of units per block (1) is from 50 to 100 units is equal to 100 minus the minimum mol percent of siloxane units (2). For example, when s+z+u is equal to 80, the minimum mol percent of siloxane units (2) is 35.2 mol percent and the maximum mol percent of siloxane units (1) is 64.8 mol percent. The equation shown above only applies when the average number of units per block (1) is from 50 to 100 units. When the average number of units per block (1) is below 50, the equation is not applicable. The minimum mol percent of polymer block (1) and the maximum mol percent of polymer block (2) is not in any manner altered. The minimum mol percent of siloxane units (2) determine the percentage below which the block copolymers provide operable release materials of the present invention. A preferred range is from 25 to 65 mol percent of (1) with the balance (2).

The release material of the present invention is prepared by mixing in any conventional manner 15 to 95 weight percent of (A) and 5 to weight percent of (B). When there is less than 15 weight percent of (A) present in the release material, the durability is reduced and the release is less desirable. When a release material is prepared from (A) and (B) in amounts outside the limits set-forth above, the release material has poor durability or poor release or both. The preferred release materials are those having 35 to 95 weight percent of (A) and 5 to 65 weight percent of (B). p The most preferred release materials are those having 50 to 95 weight percent of (A) and 5 to 50 weight percent of (B).

The diorganopolysiloxanes of (A) are well known in the art and can be purchased Commercially. For instance, the hydroxyl containing polysiloxane of (A) can be prepared as shown by U.S. Patents Nos.'2,779,776 and 2,863,897, or any of the siloxanes of (A) can be prepared as shown in fSilicones by R. N. Meals and F. M. Lewis, -Reinhold Publishing Corporation, New York, chapter 3. f I a The block copolymersof (B) can be prepared by severalmethods. Methods for the preparation of block copolymer (B) are described in copending application of Harold L. Vineent, Seri al No."361,;25 8,-filed April 20, 1964, entitled New Organosilicon Resins, which is hereby fully incorporated by reference. One method comprises reacting (C H SiX wherein X is a halogen atom with a hydroxylated polysiloxane of the average structure Hs a l 1; 3) s s 10 3 ts] wherein X is defined above, q has an average value from 1 to 1.25, w has an average value up to 0.25 and the sum of q+w does not exceed 1.25. The values for w and q include the silane added in the first reaction. The total mol percent of silicon atoms in C H SiX of the first reaction, and (CH;.,) (C H SiX. from the cohydrolysis step comprises 25 to 90 mol percent of the total number of silicon atoms present. The mol percent of the silicon atoms in the hydroxylated polysiloxane comprise from 10 to 75 mol percent of the total number of silicon atoms present. I 5

Another method described in copending application, Serial No. 361,258, filed April 20, 1964, is similar to the above method except that alkoxylated silanes are used instead of the halosilanes. The alkoxylated silanes are the same as the halosilanes except that alkoxy radicals and/or -alkyl-OCH CH O radicals replace the halide radicals. The reaction between the alkoxylated silanes and hydroxylated polysiloxanes is promoted by catalysts such as organic amines, condensation products of an aliphatic aldehyde andan aliphatic primary amine, a carboxylic acid salts of metals higher than hydrogen in the electromotive force series of metals and organic titanium compounds. The quantity of catalyst is not critical and 'as little as 0.01 percent by weight is operative.

Another method for preparing the block copolymers (B) comprises cohydrolyzing a mixture of a polysiloxane having an average of at least two silicon-bonded hydrolyzable groups per molecule, where the polysiloxanes are the same as the hydroxylated polysiloxanes except that the hydroxyl radicals are replaced by hydrolyzable groups such as halogen atoms, or alkoxy atoms, with a hydrolyzable silane as previously defined.

The foregoing method of preparing the organosilicon block copolymers of (B) are limited to diorganopolysi- 6 loxane blocks having 50 or less silicon atoms per block. Preparing block copolymers of (B) utilizing diorganopolysiloxane blocks having an average of 6 to silicon atoms per block is accomplished by the following method.

A further method for preparing the block copolymers ('B) can be found in the copending application of Robert C. Antonen, U.S. Serial No. 361,212, filed April 20, 1964, entitled Method for- Preparing Block copolymers, which is hereby fully incorporated by reference.

Another method for preparing operable block copolymers (B) is described in detail in the copending application of Darrell D. Mitchell, U.S. Serial No. 309,867, filed September 18, 1963, which is hereby fully incorporated by reference. The block copolymers (B) are prepared by reacting a hydroxylated organopolysiloxane of the formula HO[(CH (SiO) (R SiO) ]H, wherein R is a methyl, ethyl, phenyl or vinyl radical, d is from 6 to 100, and e is from 0 to 10, the sum of d-l-e does not exceed 100, and there is an average of 1.9 to 2.0 organic radicals per silicon atom, with a coupling compound including SiX X SiOSiCl X SiOSiBr c xasios iosicu or X SiSiX where X is a halogen atom. There is at least one molecule of the coupling compound per hydroxyl group present in the hydroxylated organopolysil-oxane. Silanes of the formula (C H (CH SiX where X is a halogen and q and w have previously been defined, hydrolysis products of silanes or mixtures of the silanes and the hydrolyzed product are mixed with the reaction product between the hydroxylate-d organ-opolysiloxane and the coupling compound. The silanes and hydrolysis products thereof are added in'amounts to produce block copolymers (B) which are operable in this invention. The mixture thus formed, is hydrolyzed in the presenceof water.

, 'The release material of this invention can be used as a mixture of the two components (A) and (B) per se. This is not the most convenient method of using the release material, but certain applications find this very adaptable. Uses and applications are presented below. The release material can be put into organic solvent solutions. Organic solvents conventionally used in the polysiioxane art can be used. Suitable organic solvents include hydrocarbons such as heptane, cyclohexane, methylcyclopentane, benzene, toluene, xylene, naphtha and mineral spirits; halocarbons and halohydrocarbons such as perchloroethylene, tetrachlorodifiuoroethane, chlorothene, trichlorotrifluoroethane, chlorobenzene, carbontetrachloride, trichloromonofluoromethane, dichlorodifluoromethane, monochlorotrifiuoromethane, carbon tetrafiuoride, dichloromonofiu-oromethane, monochlorodifiuoromethane, dichlorotetrafiuoroethane, monochloropentafluoroethane, dibromodifiuoromethane, monobromotrifluorornethane, trifiuoromethane, dibromomonochlorotrifluoroethane, and dibrom-otetrafiu-oroethane; ethers, such as diethylether, dibutylether, methylbutylether, methylamylether, and methylhexylether; halogenated ethers such as 2,2-dibromodiethylether and 3,3-dichlorodibutylether; ketones such as acetone, methylethylektone, methylbutylketone, mesityl oxide, isophorone and methylamylketone and esters such as butylacetate, ethyl acetate, isopropyl acetate, amyl acetate, ethyl butyrate, CH COOC H OCH CH COOC H OC H CH COOC H OC H 0C H and CH COOC H OCOCH The release material of this invention can also be put into aqueous emulsion. The aqueous emulsion of the release material is prepared by conventional emulsifying techniques. The release material is emulsified with water and one or more emulsifying agents. The emu sifying agents can be cationic, anionic or nonionic. Any of the conventional emulsifying agents can be used such as cationic emulsifying agents such as aliphatic fatty amines and their derivatives such as dodecylamine acetate, octadecylamine acetate and acetates of the amines of tallow fatty acids; homologues of aromatic amines having fatty chains such as dodecyl lanolin, fatty amides derived from aliphatic diamines such as undecylamidazoline, fatty amides derived from di-substituted amines such as oleylaminodiethylamine, derivatives of ethylene diamine, quaternary ammonium compounds such as di-octadecyldimethyl ammonium chloride, didodecyldimethyl ammonium chloride and dihexadecyldimethyl ammonium chloride, amide derivatives of amino alcohols such as beta-hydroxyethylstearyl amide, amine salts of long chain fatty acids, quaternary ammonium bases derived from fatty amides of di-substituted diamines such as oleylbenzyl aminoethylene, diethylamine hydrochloride; quaternary ammonium bases of the benzamidazolines such as methylheptadecyl benzamidazoline hydrobromide; basic compounds of pyridinium and its derivatives such as cetyl pyridiniu m chloride; sulfonium compounds such as octadecyl sulfonium methyl sulfate, quaternary ammonium compounds of betaine such as betaine compounds of diethylaminoacetate acid and octadecyl chloromethyl ether; urethanes of ethylenediamine such as the condensation products of stearic acid and diethylenetriamine, polyethylenediamine and polypropylated ethanolamine.

Suitable non-ionic emulsifying agents are the saponines condensation products of fatty acids with ethylene oxides such as dodecylether of tetraethylene oxide, condensation products of ethylene oxide and sorbitan monolaurate, condensation products of ethylene oxide and sorbitan trioleate, and condensation products of phenolic compounds having side chains with ethylene oxide such as cond nsation products of ethylene oxide with isodecylphenol, condensation products of fatty alcohols and ethylene oxide such as octadecylalcohol and ethylene oxide and amine derivatives such as polymerized ethylene amine and N- octadecyl-N,N-ethylene amide.

Suitable anionic emulsifying agents are alkali metal sulforicinates, sulfonated glycerol esters of fatty acids, such as sulfonated monoglycerates of coconut oil acids, salts of sulfonated monovalent alcohol esters such as sodium oleyl isothionate, amides of amino sulfonic acids such as the sodium salt of oleyl methyl tauride, sulfonated products of fatty acid nitriles such as palmidonitrile sulfonate, sulfonated aromatic hydrocarbons such as sodium alphanaphthylene monosulfonate, condensation products of naphthalene sulfonic acids with formaldehyde, sodium octahydroxyanthracene sulfonate and alkylaryl sulfonates having one or several alkyl groups of eight or less carbon atoms.

Also operable are mixtures of emulsifying agents. Any of the emulsifying agents can be mixed except that the cationic emulsifying agents cannot be mixed with the anionic emulsifying agents.

The emulsions of the release material can have a wide variety of concentrations of ingredients. The emulsions can have from 0.1 to 50 weight percent release material based on the total weight of the emulsion, preferably 1 to 30 percent release material. The emulsion can have 0.1 to Weight percent of emulsifying agent in addition to the release material and the remainder water. The emulsion can also have up to 25 weight percent organic solvent from the previously defined solvents for the release material. Preferably, the emulsion has up to weight percent organic solvent.

The release materials of the present invention are particularly useful as release coatings for the release of burned foods from surfaces. The release materials can be applied in several forms and several methods. The release materials of this invention are particularly useful for coating ovens to prevent burned foods and greases from adhering to the oven surface. Although the release materials are suitable as release coatings on surfaces other than an oven surface, the outstanding property of the release material is that it can be used o in an oven with excellent results and provides an oven which is readily cleanable without the use of high potency cleaners and abrasives such as steel Wool.

A release coating can be applied from an aerosol package. The compositions of release materials operable are those compositions of a diorganopolysiloxane (A) with a viscosity at 25 C. from 50,000 cs. to 750,000 cs. Preferably, the viscosity of (A) is from 50,000 cs. to 500,000 cs. at 25 C. The release material in an aerosol package can be applied from any conventional commercial aerosol package. The release material can be dissolved in an organic solvent. Any of the previously disclosed solvents for the release material can be used, but it is particularly advantageous to use organic solvents which are non-toxic and non-flammable as a housewife is potentially the main consumer although industrial bakeries and other food makers can also use this invention to advantage. Preferably then, the preferred organic solvents for release material in aerosol packages are those such as the halogenated organic solvents such as perchloroethylene, tetrachlorodifluo-roethane, chlorothene, trichlorotrifluoroethane, trichloromonofluoromethane, dichlorodifiuoromethane, monochlorotrifluoromethane, carbon tetrafluoride, dichloromonofluoromethane, dichlorotetrafluoroethane and monochloropentafiuoroethane. Solvents such as those just named can be used alone or mixed with other solvents as previously described. The organic solvents used should include an aerosol propellent. Many of the halogenated solvents are not propellents, but other conventional aerosol propellents can also be used. The release material can be in the organic solvent and packaged in aerosol packages. Preferably, the release material is present in amounts from 0.1 to 20 weight percent based on the weight of the total solution. Most preferably, the release material is present from 0.3 to 10 weight percent. The coating is sprayed from the aerosol package so that the mist comprising the release material and solvents covers the object to be coated evenly and preferably in a thin film.

The release material can also be applied from a pretreated applicator such as a pretreated cloth, a pretreated sponge or a pretreated porous pad such as a felt pad containing the release material per se or the release material in an organic solvent. The applicator should be pliable and porous. The pretreated applicator is prepared by conventional methods of'getting the release material into the porous applicator. The porous applicator can be immersed in the release material until it has become sat urated with the release material. The pretreatedcloth or pad containing the release material can be applied to surfaces by rubbing or wiping. A slight pressure on the porous pretreated applicator causes the release material to come outof the applicator and be deposited on the surface such as an oven surface. Any concentrations of release material in organic solvents can be used, preferably when a cloth or pad is used the organic solvent is present in as small amounts as possible, just enough to make it easy and convenient to apply. Any of the release materials of this invention can be used for pretreating applicators such as those described above.

Organic solvent solutions of the release material can also be used'to dip parts to be coated. The organic solvent solutions can also be applied from any conventional bottle with a cloth or other device.

The release material can also be applied from an aqueous emulsion as previously disclosed. The aqueous emulsion of the release material can be applied from a conven tional bottle with the aid of a cloth, a sponge or other similar device. A squeeze bottle such as polyethylene or polypropylene bottle, aerosol package or other conventional container with or without spreading aids. The aqueous emulsion of the release material can be used in a concentrated formcomprising such as 20 to 50 weight percent release material, 0.1 to 10 weight percent emulsifying agent and the remainder water. These concentrated emulsions can be used as such or diluted just before use.

Preferably, the emulsions for use by the housewife are already in a diluted and easily applied form comprising preferably from 0.5 to 10 Weight percent release material, 0.1 to weight percent emulsifying agent and the remainder water.

The release materials of the present invention are designed primarily for use in ovens, particularly ovens used for cooking of food. The release materials therefore must pass several rigorous requirements. The release material is a mixture of two components, a diorganopolysiloxane (A) and a siloxane block copolymer (B). The release material of the present invention is heat stable. The viscosity is stable over the temperature range involved in ovens. The release material does not decompose to any significant degree from room temperature up to 600 F. The release material of the present invention retains its properties at 600 F. for more than 100 hours. The release material is clear and does not discolor over long periods of use. The release material is easy to apply in any form and in a variety of ways. A release coating is durable as it will last over a long period of time retaining its release properties and it will retain effective release over long periods of time even at high temperatures. The release material will also release repeatedly from the same spot. The release material adheres firmly to the surfaces of ovens such as metal, porcelain or enameled surfaces and yet the rel-ease material can readily be removed from the oven surface. The release material will release burned foods and greases readily. The burned foods and greases have a tendency to stain and the release material will prevent staining of the oven surface and will also develop only slight stains itself which can readily be removed. The release material has good shelf life. The release material is easy to replace. When a spot has become stained from repeated release of burned food, the release material can readily be removedby scouring pow der and very little rubbing, as little as once over with a cloth and scouring powder. Once removed, either entirely or in one spot, the release material can be easily replaced such as by spraying with an aerosol package, wiping on a solution, using a pretreated cloth orusing an emulsion either from an aerosol package or a squeeze bottle with the aid of an applicator. There are no problems of the coating not adhering to the release material already present or to a surface which still retains a minute amount. The release material of the present invention can be applied over a surface which is not entirely clean and will "function just as effectively as if the surface 'was absolutely clean from any traces of impurities. This is particularly of interest to a housewife who uses this release material. If she has recently cleaned the oven, but it was used since the cleaning and is not yet dirty enough for another cleaning, she can apply the release material directly on the oven without cleaning first. This saves her time and effort and also provides an oven which will be very readily cleanable when spillage from cooking and grease accumulation demands. An emulsion of the present release material is particularly advantageous for this purpose. The emulsion will clean the oven surfaces and at the same time deposit a coating of the release material over the cleaned surface. The exact reason why the emulsion is such a good cleaning agent and will also deposit a release coating on the surface is not entirely understood, but it is believed that the emulsifying agent, the release material and the water provide an especially effective means for solubilizing the dirt and grease holding it in solution and depositing a release coating on the cleaned surface before the dirt and grease have an oppor tunity to redeposit on the cleaned surface. Besides the emulsifying agents, other cleaning aids can be added to the emulsions such as hard surface cleaners such as trisodium phosphate.

The release material is also non-toxic, is non-flammable and solvent solutions can be made non-flammable by the proper selection of solvents when used and is economical.

The release material is very useful for coating an oven, whether it is a commercial oven or a home oven to prevent sticking of burn-ed foods and greases and to make the oven readily cleanable without the use of caustics, ammonia, high potency solvents or steel wool. The release material should not contain curing agents or other ingredients which can degrade the polymer. Because the release material is completely satisfactory for an oven, the release material also has many other utilities such as providing release of undesirable materials from porcelain, metal or enameled surfaces.

The release material can be coated on skillets, cookie sheets, bread pans, cake pans, sauce pans, casseroles, waffle irons and other cooking utensils where sticking of food appears to be a problem. The release material can also be used, especially the emulsions, to prevent greases and food from adhering to refrigerator surfaces, the outside surfaces of stoves, tile surfaces and other surface areas of a kitchen where a grease film is likely to deposit. The emulsion will clean the surface at the same time it deposits a protective release coating. Another particularly useful application of the present release material is for coating outdoor and indoor barbecue grills and the like. The barbecue can be coated almost entirely with th release material of this invention. The bars can be coated, the hood and accessory parts, and the implements used with the barbecue can be coated. The release material is quick and easy to apply. Also the food will not burn onto the bars, thus providing easy removal of the food. The release coating can be applied by any of the previously discussed methods and repeated application of the release material to the extremely hot areas, where removal is frequent because of char formation, can be done as often as needed.

The following examples are illustrative only and should not be construed as limiting the invention which is properly delineated in the appended claims.

The preparation of a block copolymer (B): A dispersion was formed bymixing in a three-necked flask equipped with a thermometer and an agitator 222 g. of a hydroxylated essentially dimethylpolysiloxane having an average of 39 silicon atoms per molecule, 360 g. of toluene and 1900 g. of water, and enough agitation was applied to form a dispersion consisting of two phases, an essentially aqueous phase and an essentially diorganopolysiloxane phase. In a quart container, 381 g. (1.8 moles) of phenyltrichlorosilane, 38 g. (0.2 mole) of phenylmethyldichlorosilane and 360 g. of toluene were mixed and then added to the above dispersion over a two minute period, there being sufficient agitation to maintain the dispersion. The temperature increased from 20 to 55 C. during the addition. The byproduced hydrogen chloride formed on the addition gave a 10 weight percent hydrogen chloride solution in water. The dispersion was stirred for 30 minutes after the addition. The aqueous phase was separated from the organopolysiloxane phase consisting of a block copolymer and toluene by decanting. The organopolysiloxane phase was washed once with water and then azeotroped until the temperature reached 116 C. at which time the solution had a solids content of 46.9 weight percent. The solvent was removed by vacuum stripping to C.

A portion of the above siloxane block copolymer was bodied with 0.1 weight percent zinc as zinc octoate by refluxing a solution of the above block copolymer for 6.5 hours. The bodied block copolymer was vacuum stripped to 155 C. to remove the solvent and was designated block copolymer (B).

Example 1 A release material was prepared by mixing 10 g. of an essentially trimethylsiloxy-endblocked dimethylpolysiloxane gum having a viscosity greater than 1,000,000 cs. at 25 C., 5 g. of the stripped bodied block copolymer (B) prepared above. A solution of the release material was 1 1 prepared by dissolving it in 42 g. of a mixed hydrocarbon solvent and 43 g. of chlorothene. The solution of the release material was wiped on an enameled testing panel and then heated at 425 F. for 15 minutes. After the heating period a blob of red raspberry pie filling was dropped on the treated panel and heated again at 425 F. for 15 minutes. The burned iPiB filling slid ofr easily and a slight stain remained. The stain was readily removed by rubbing over the stain with scouring power.

Example 2 When any of the following diorganopolysiloxanes are substituted for the trimethylsiloxy-endblocked dimethylpolysiloxane of Example 1, equivalent release materials are obtained.

A. An essentially trimethylsiloxy-endblocked dimethylpolysiloxane having a viscosity of 60,000 cs. at 25 C.

B. An essentially trimethylsiloxy-endblocked dimethylpolysiloxane having a viscosity of 1,000,000 cs. at 25 C.

C. An essentially hydroxyl-endblocked dimethylpolysiloxane having a viscosity of 50,000 cs. at 25 C.

D. An essentially dimethylpolysiloxane containing mol percent monomethylsiloxane units, 3 mol percent trimethylsiloxane units and 2 mol percent silicon-bonded hydroxyl radicals and having a viscosity of 100,000 cs. at 25 C.

E. A hydroxyl-endblocked dimethylpolysiloxane gum having a viscosity of 6,000,000 cs. at 25 C.

Example 3 When 3 g. of an essentially hydroxylendblocked diorganopolysiloxane composed of 95 mol percent dimethylsiloxane units and 5 mol percent phenylmethylsiloxane units and having a viscosity of 750,000 cs. at 25 C. and 7 g. of a siloxane block copolymer (B) prepared as above consisting of 35 mol percent siloxane blocks composed of dimethylsiloxane units and having 20 silicon atoms per black and 65 mol percent of siloxane blocks composed of 75 mol percent C H SiO units and 25 mol percent (C T-I (CH )SiO units are mixed in 90 g. of xylene, a release material solution is obtained. When the release material solution is applied to an oven surface with a cloth, the oven surface is ready cleanable from spilled pie filling, greases and casseroles. The burned char can readily be removed from the oven surface by wiping with a cloth and any stains can be removed with scouring powder.

Example 4 When 1.5 g. of diorganopolysiloxane composed of 95 mol percent of dimethylsiloxane units, 5 mol percent ethylmethylsiloxane units, and endblocked with dimethylvinylsiloxane units having a viscosity of 500,000 cs. at 25 C., and 8.5 g. of a siloxane block copolymer composed of 45 mol percent of siloxane blocks of a diorganop'olysiloxane consisting of 95 mol percent dimethylsiloxane units and 5 mol percent of phenylmethylsiloxane units and having an average of 72 silicon atoms per block and 55 mol percent of siloxane blocks consisting of 95 mol percent monophenylsiloxane units and 5 mol percent monomethylsiloxane units are mixed in 35 g. of perchloroethylene and 30 g. of dibutylether, a releasematerial solution is obtained. When the release material is applied to an oven surface, the surface becomes readily cleanable from any food deposited on the surface whi char.

Example 5 When the siloxane block copolymer of Example 4 is replaced by a siloxane block copolymer having 70 mol percent siloxane blocks composed of dimethylsiloxane units and having 6 silicon atoms per block and 30 mol percent siloxane blocks composed of monophenylsiloxane units, an equivalent release material is obtained.

12 Example 6 When 9 g. of a diorganopolysiloxane composed of 98 mol percent dimethylsiloxane units and 2 mol percent methylvinylsiloxane units and endblocked with trimethylsiloxane units and having a viscosity of 75,000 cs. at 25 C. and 1.0 g. of a siloxane block copolymer consisting of 10 mol percent of siloxane blocks consisting of dimethylsiloxane units and having 35 silicon atoms per block and mol percent of siloxane blocks composed of 90 mol percent monophenylsiloxane units and 10 mol percent phenylmcthylsiloxane units are mixed with g. of a solvent consisting of 30 Weight percent chlorothene, 40 weight percent trichlorotrifluoroethane, and 30 Weight percent monochlorodifiuoromethane in a conventional aerosol package a release material aerosol packaging composition is formed. When a thin coating is deposited on a test panel by spraying With the mist of the aerosol package containing the aerosol composition and then tested as described in Example 1, equivalent results are obtained.

Example 7 Wt. Percent Solvent Mixture Release Material 0.1 55 weight percent chlorothene, 30 weight percent trichloromonofiuorornethane, and 15 weight percent dichlorodifiuoromethane.

0.5.". 20 weight percent perchlorethylene and 80 Weight percent dichlorotetrafluoroethane.

10.0 5 weight percent xylene, 15 weight percent chlorothene, 45 Weight percent dichloromonofiuoromethane, and 35 weight percent dibromotetrafluoroethano.

20.0 10 weight percent chlorothene, 60 weight percent trichloromonofiuorornethanc, and 30 weight percent Inonochloropentafluoroeth ane.

Example 8 When 3.5 g. of a trimethylsiloxy-endblocked dimethylpolysiloxane having a viscosity of 50,000 cs. at 25 C. and 6.5 g. of a siloxane block copolymer prepared by the method outlined above, and consisting of 40 mol percent of siloxane blocks composed of 90 mol percent dimethylsiloxane units, 5 mol percent monovinylsiloxane units, 5 mol percent ethylmethylsiloxane units and having an average of silicon atoms per molecule and 60 mol percent of siloxane blocks composed of 80 mol percent monophenylsiloxane units and 20 mol percent phenylmethylsiloxane units are mixed, a release material is produced. When 0.3 g. of the above release material is mixed in a conventional areosol package in 99.7 g. of a solvent mixture composed of 18 weight percent chlorothene, 43 weight percent trichloromonofluoromethane and 39 weight percent dichlorodifluoromethane, a release material aerosol packaging composition is produced. When a mist of the spray from the above aerosol package is sprayed on an enamel oven surface in a thin film and the solvent evaporated, any char from food forming thereon can readily be removed by wiping with a cloth and the stain can be removed with securing powder and light rubbing.

Example 9 When 50 g. of a trimethylsiloxy-endblocked dimethylpolysiloxane having a viscosity of 100,000 cs. at 25 C. and 50 g. of the stripped siloxane block copolymer (B) 13 described above are mixed, a release material is formed. When any of the following materials in the amounts indicated are emulsified in a high speed emulsifier, release material emulsions are formed.

' 14 2. The release material in accordance with claim 1 wherein (A) is present in an amount from 35 to 95 weight percent and (B) is present in an amount from 5 to 65 weight percent.

TABLE Wt. Percent Wt. Percent Wt. Percent Wt. Percent Release Emulsifying Agent Emulsitying Organic Solvent Organic Water Material Agent Solvent 10.0 Dodecyl lanolin 5. 0. 0 85 5.0 Condensation poduet of ethylene oxide and 2. 0 10. 0 83 sorbitan mono] a'uate. 30.0. Sodium salt of oleyl methyl tauride 8. 0 Ohlorothene toluene 8 37 0.1 Condensation product of ethylene oxide and 1. 0 Toluene 0 93. 9

isodecylphenol. 1.0 Sodium oetahydroxylanthraeene sulfonate 10.0 0.0 89

Example 10 When 60 g. of the diorganopolysiloxane of Example 2(B) and 40 g. of the siloxane block copolymer of Example 1 are mixed with 50 g. of chlorothene, a release material is formed. When a felt pad is allowed to become saturated with the release material by immersing the felt pad in the release material, a pretreated applicator is formed. When the pretreated felt pad is wiped over a metal skillet, an oven surface or a grill, a coating of the release material is left thereon. When food products which are sticky or are charred are deposited on the surfaces, they readily can be removed from the surface.

Example 11 When any of the emulsions of Example 9 are wiped over a porcelain surface, such as a refrigerator or a stove, the surface is cleaned and also protected by a film of the release coating.

- That which is claimed is:

1. A release material consisting essentially of ;(A)' a dior'ganopolysiloxane of the unit formula R (OH) SiO wherein R is a monovalent radical selected from the group consisting of alkyl radicals, alkenyl radicals and aryl radicals, n has an average value from 1.98 to 2.0024 inclusive, at least 90 percent of the silicon atoms having two methyl radicals per silicon atom bonded to the silicon atom through silicon-carbon bonds, m has an average value of not more than 0.02, the sum of m+n does not exceed 2.0024, said diorganopolysiloxane having a viscosity of at least 50,000 cs. at 25 0, there being no more than 2 mol percent of the units with alkenyl radicals attached to the silicon atom through siliconcarbon bonds,

' '(B) ablock copolymer consisting essentially of (1) polymer blocks of the average structure [(CH SiO] [R SiO] [R'SiO wherein R is a monovalent radical selected from the group consisting of methyl, ethyl, vinyl and phenyl radicals, the sum of s+t+u has an average value from 6 to 100 inclusive and t and u each have a value of up to 10 percent of the sum of s+t+u,

(2) polymer blocks of the average unit formula (C H (CH SiO wherein q has an average value from 1 to 1.25 inclusive, w has an average value of up to 0.25 inclusive and the sum of q+w does not exceed 1.25,

the siloxane units in 1) being from 10 to 75 mol percent and the siloxane units (2) being from 25 to 90 mol percent of the total siloxane units in said block copolymer, the minimum mol percent of siloxane units (2) when the sum of s+t+u has an average value of from 50 to 100 being determined by the equation 50M/S+0.1S=30,

where M is the minimum mol percent of siloxane units (2) and S is the sum of s+t+u, there being present 15 to 95 inclusive weight percent of (A) and 5 to 85 inclusive weight percent of (B), each based on the combined weight of (AH-(B).

3. The release material in accordance with claim 1 wherein (A) is present in an amount from 50 to weight percent and (B) is present in an amount from 5 to 50 weight percent.

4. The release material in accordance with claim 1 wherein n has an average value from 1.98 to 2.0020 inclusive, and the sum of m+n does not exceed 2.0020.

5. The release material in accordance with claim 4 wherein (A) is present in an amount from 50 to 95 weight percent and (B) is present in an amount from 5 to 50 weight percent.

6. The release material in accordance with claim 1 wherein the, sum of s+t+u is from 20 to 75 inclusive, q has an average value from 1 to 1.20 inclusive, w has an average value up to 0.20 and the sum of w+q does not exceed 1.20.

7. The release material in accordance with claim 6 wherein (A) is present in an amount from 50 to 95 weight percent and (B) is present in an amount from 5 to 50 weight percent.

8. The release material in accordance with claim 1 wherein n has an average value from 2,0000 to 2.0020 inclusive, m has an average value of not more than 0.0020, the sum of m-l-n does not exceed 2.0020 and said diorganopolysiloxane having a viscosity of at least 100,000 cs. at 25 C. p 9. The release material in accordance with claim 8 wherein (A) is present in an amount from 50 to 95 weight percent and (B) is present in an amount from 5 to 50 weight percent. I

10. The release material in accordance with claim 8 in which I is 0, the sum of s+u has an average value from 20 to 75 inclusive, R is a methyl radical, it has a value up to 5 percent of the sum of s-l-u, q has an average value from 1 to 1.20 inclusive, w has an average value up to 0.20, the sum of q+w does not exceed 1.25, the siloxane units in (1) being from 25 to 65 mol percent and the siloxane units in (2) being from 35 to 75 mol percent of the total siloxane in said block copolymer.

11. The release material in accordance with claim 10 wherein (A) is present in an amount from 50 to 95 weight percent and (B) -is present in an amount from 5 to 50 weight percent.

12. A release material in accordance With claim 1 in which (A) is (CH SiO[(CH SiO] Si(CH wherein p has an average value of at least 845.

13. A release material in accordance with claim 12 in which p has an average value of at least 1010.

14. A release material in accordance with claim 6 in which (A) is (CH SiO[(CH SiO] Si(CH wherein 12 has an average value of at least 845.

15. A release material in accordance with claim 14 in which p has an average value from 845 to 1635 inclusive.

16. A release material solution consisting essentially of the release material of claim 1 and an organic solvent.

17. A release material solution consisting essentially of the release material of claim 3 and an organic solvent.

18. A release material solution consisting essentially of the release material of claim 15 and an organic solvent.

15 19. A release material solution in accordance with claim 16 in which said release material is present in an amount from 0.1 to 20 weight percent based on the combined Weight of the release material and the organic solvent.

20. A release material aerosol packaging composition comprising a release material consisting essentially of (A) a diorganopolysiloxane of the unit formula R (OH) SiO wherein R is a monovalent radical selected from the group consisting of alkyl radicals, alkenyl radicals and aryl radicals, n has an average value from 1.98 to 2.0024 inclusive, at least 90 percent of the silicon atoms having two methyl radicals per silicon atom bonded to the silicon atom through silicon-carbon bonds, m has an average value of not more than 002, said diorganopolysiloxane having a viscosity from 50,000 cs. to 750,000 cs. at 25 0., there being no more than 2 mol percent of the units with alkenyl radicals attached to the silicon atom through silicon-carbon bonds, the sum of n+m does not exceed 2.0024, (B) a block copolymer consisting essentially of (1) polymer blocks of the average structure [(CH SiO] [R SiO] [R'SiO wherein R is a monovalent radical selected from the group consisting of methyl, ethyl, vinyl and phenyl radicals, the sum of s+z+u has an average value from 6 to 100 inclusive, and t and u each have a value of up to 10 percent of the sum of s-l-t-l-u, and (2) polymer blocks of the average unit formula (C H (CI-l SiO wherein q has an average value from 1 to 1.25 inclusive, w has an average value of up to 0.25 inclusive, and the sum of q+w does not exceed 1.25, the siloxane units in (1) being from to 75 mol percent and the siloxane units in (2) being from 25 to 90 mol percent of the total siloxane units in said block copolymer, the minimum mol percent of siloxane units (2) when the sum of s-i-t-l-u has an average value from 50 to 100 at least one halogenated organic solvent present and an aerosol propellant.

21. A release material aerosol packaging composition in accordance with claim 20 in which said release material is present in an amount from 0.3 to 10 weight percent based on the total weight of the ingredients.

22. A release material aerosol packaging composition comprising from 0.1 to 20 wei ht percent of the release material of claim based on the total Weight of the 1% ingredients, an organic solvent, said organic solvent having at least one halogenated organic solvent present and a aerosol propellant.

23. A release material aerosol packaging composition in accordance with claim 22, in which said release material is present in an amount from 0.3 to 10 weight percent based on the total weight of the ingredients.

24. A release material aerosol packaging composition in accordance with claim 20 in which said organic solvent consists of chlorothene, trichloromonofiuoromethane and dichlorodifluoromethane.

25. A release material areosol packaging composition in accordance with claim 21 in which said organic solvent consistis of chlorothene, trichloromonofiuormethane and dichlorodifiuoromethane.

26. A release material aerosol packaging composition in accordance with cQaim 22 in which said organic solvent consists of chlorothene, trichloromonofiuoromethane and dichlorodifluoromethane.

27. A release material aerosol packaging composition in accordance with claim 23 in which said organic solvent consists of chlorothene, trichloromonofiuoromethane and dichlorodifluorornethane.

28. An aqueous emulsion comprising from 0.1 to weight percent of the release material of claim 1, from 0.1 to 10 Weight percent of an emulsifying agent and water, the weight percent being based on the total weight of the ingredients.

29. An aqueous emulsion in accordance with claim 28 in which the release material is present in an amount from 1.0 to 30 weight percent.

30. An aqueous emulsion in accordance with claim 29 in which there is present an organic solvent in an amount up to 25 weight percent.

31. A pretreated applicator comprising a flexible absorbant porous substrate essentially saturated with the release material of claim 1.

32. An even surface coated with the release material of claim 11.

33. A skillet surface coated with the release material of claim 1.

34. A porcelain surface coated with the release material of claim 1.

35. A metal surface coated with the release material of claim 1.

36. An enameled surface coated with the release material of claim 1.

References Cited by the Examiner UNITED STATES PATENTS 2,793,197 5/1957 Brown 26033.8 2,833,441 5/1958 Hedlund 26029.l 3,002,946 10/1961 Thomas 260-29.1 3,202,542 8/1965 Poje 260-291 3,231,532 1/1966 Medic 26029.1

MURRAY TILLMAN, Primary Examiner.

J. C. BLEUTGE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,308,080 March 7, 1967 Sharon R. Haenni It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, lines 62 and 64, for "2.000", each occurrence,

read 2.0000 column 4, line 17, for "1.8" read 1.18 column 6, lines 22 to 25, the formula should appear as shown below instead of as in the patent:

X SiOS\iOSiCl column 6, line 62, for "methylethylektone" read methylethylketone column 11, line 39, for "black" read block column 14, line 38, for "2,0000" read 2.0000

Signed and sealed this 7th day of November 1967.,

(SEAL) Attest:

EDWARD M.FLETCHER,JR. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A RELEASE MATERIAL CONSISTING ESSENTIALLY OF (A) A DIORGANOPOLYSILOXANE OF THE UNIT FORMULA RN(OH)MSIO4-N-M/2 WHEREIN R IS A MONOVALENT RADICAL SELECTED FROM THE GROUP CONSISTING OF ALKYL RADICALS, ALKENYL RADICALS AND ARYL RADICALS, N HAS AN AVERAGE VALUE FROM 1.98 TO 2.0024 INCLUSIVE, AT LEAST 90 PERCENT OF THE SILICON ATOMS HAVING TWO METHYL RADICALS PER SILICON ATOM BONDED TO THE SILICON ATOM THROUGH SILICON-CARBON BONDS, M HAS AN AVERAGE VALUE OF NOT MORE THAN 0.02, THE SUM OF M+N DOES NOT EXCEED 2.0024, SAID DIORGANOPOLYSILOXANE HAVING A VISCOSITY OF AT LEAST 50,000 CS. AT 25%C., THERE BEING NO MORE THAN 2 MOL PERCENT OF THE UNITS WITH ALKENYL RADICALS ATTACHED TO THE SILICON ATOM THROUGH SILICONCARBON BONDS, (B) A BLOCK COPOLYMER CONSISTING ESSENTIALLY OF (1) POLYMER BLOCKS OF THE AVERAGE STRUCTURE ((CH3)2SIO)S(R''2SIO)T(R''SIO1.5)U, WHEREIN R'' IS A MONOVALENT RADICAL SELECTED FROM THE GROUP CONSISTING OF METHYL, ETHYL, VINYL AND PHENYL RADICALS, THE SUM OF S+T+U HAS AN AVERAGE VALUE FROM 6 TO 100 INCLUSIVE AND T AND U EACH HAVE A VALUE OF UP TO 10 PERCENT OF THE SUM OF S+T+U, (2) POLYMER BLOCKS OF THE AVERAGE UNIT FORMULA (C6H5)CH3)WSIO4-W-Q/2, WHEREIN Q HAS AN AVERAGE VALUE FROM 1 TO 1.25 INCLUSIVE, W HAS AN AVERAGE VALUE OF UP TO 0.25 INCLUSIVE AND THE SUM OF Q+W DOES NOT EXCEED 1.25, THE SILOXANE UNITS IN (1) BEING FROM 10 TO 75 MOL PERCENT AND THE SILOXANE UNITS (2) BEING FROM 25 TO 90 MOL PERCENT OF THE TOTAL SILOXANE UNITS IN SAID BLOCK COPOLYMER, THE MINIMUM MOL PERCENT OF SILOXANE UNITS (2) WHEN THE SUM OF S+T+U HAS AN AVERAGE VALUE OF FROM 50 TO 100 BEING DETERMINED BY THE EQUATION 50M/S+0.1S=30, WHERE M IS THE MINIMUM MOL PERCENT OF SILOXANE UNITS (2) AND S IS THE SUM OF S+T+U, THERE BEING PRESENT 15 TO 95 INCLUSIVE WEIGHT PERCENT OF (A) AND 5 TO 85 INCLUSIVE WEIGHT PERCENT OF (B), EACH BASED ON THE COMBINED WEIGHT OF (A)+(B). 